1. Field of the Invention
This invention pertains to an elongated roof valley strip having a channel shaped cross-section and opposed flanges for conducting precipitation runoff of sloping roof surfaces.
2. Background Art
In conventional sloping roof construction the intersection of two sloping roof surfaces is normally covered by an elongated sheet member forming a covering for the roof surface intersection and also forming a trough for conducting precipitation runoff from the intersecting roof surfaces. Conventional roof valley strips are formed from relatively thin sheet metal or the like and are merely bent or deflected during the laying of the roof to form a relatively shallow concave curved surface with opposed flanges of the strip lying under the roof shingles. One disadvantage with conventional roof valley strip arrangements is that during periods of heavy rainwater runoff, for example, the flow of water down one roof surface will be of such velocity and momentum as to run into the trough portion of the strip, over the opposing strip flange and under the edge of the roof covering. This runoff may be of sufficient velocity to run to the edge of the flange portion and thereby leak into the interior of the building or at least result in leakage to the subroofing surface which can result in eventual damage to the roof from trapped moisture.
Another problem with conventional valley strips is in the repair or covering of roofs having a first roof covering such as, for example, wood shingles, which are of substantial thickness. In the use of a conventional valley strip to overlie the previous shingle layer, a substantial gap is formed between the original valley strip and the overlying new valley strip which, if walked on or otherwise impinged on, may damage the overlying valley strip or at least cause bending and deformation of the valley strip. In the former case, if the new valley strip is punctured, precipitation runoff will, of course, run under the new valley and may result in damage to the roof or leakage therethrough. In the latter instance, the bending or deformation of the unsupported trough portion of the new valley strip will mar the appearance of the roof. Moreover, if the valleys are formed of conventional galvanized sheet steel any bending or deflection of the valley strip tends to break the protective coating resulting in early onset of corrosion of the base metal.
The abovementioned problems, which are particularly acute in recovering roofs having an underlying or first surface of shingles of substantial thickness, have been overcome with the improved valley strip construction of the present invention which is adapted to minimize the chance of leakage of precipitation runoff through the roof structure by redirecting the runoff flow in a more positive manner to prevent migration of the runoff water over the opposed flange surfaces of the strip. Moreover, the improved valley strip construction of the present invention forms a trough portion which has a bottom surface which is recessed to minimize contact by a person walking on the roof and to place the bottom surface of the valley trough closely adjacent to the underlying roof covering whereby adequate support of the valley strip is provided.